GB2213093A - A mandrel - Google Patents

Abstract

A mandrel comprises at least two parts (44 and 46 for example) which are joined together by means of an elongate component (76). The latter passes through at least one of the parts (44 for example) and has one end attached to one of the parts (44 for example) and its other end attached to the other part or another part (48 for example). Means (74) are provided for releasing the elongate component (76) from at least one of its points of attachment (60). The component (76) may be a chain. The mandrel may be used to form a hose (10, Fig 1 not shown) built up from layers of neoprene, stainless steel braiding and aromatic polyamide or aramid fibres or cloth. <IMAGE>

Description

A mandrel The present invention relates to a mandrel for use in the manufacture of a hose, especially but not exclusively a hose for use in marine machinery compartments, for example for the passage of fuel oil, lubricating oil, sea water, or fresh water. It also relates to the manufacture of such a hose.

In our prior patent specification No. 1,397,432 we describe a hose made of a flexible material through the tubular wall of which extends tubular stainless steel reinforcing braiding. Each end of the hose terminates in a connecting flange. In order to reduce the likelihood with which a flanged end is sheared from the rest of the hose, a pair of flanged rings is embedded within the flange of the hose. The annular flange of each ring is positioned centrally within the hose flange, so that the flanges of the rings themselves extend in the same general plane as the hose flange, transversely of the tube of the hose itself.

Each flanged ring has a tubular portion extending inwardly into the hose. These two tubular portions fit one inside the other and clamp the stainless steel braiding between them. The stainless steel braiding is also splayed out between the flanges of the rings at 90 degrees to the rest of the tubular braiding. Each flange is crimped to form two concentric ribs, the convex sides of the ribs on one of the flanges fitting into the concave recesses of the ribs on the other flange. In this way, the braiding is trapped between the flanged rings.

It has been found that the forces which may be encountered with particularly large hosing, having a bore of diameter in the range from about 65mm to about 130mm, or sometimes even with a hose of smaller diameter where the pressure is considerable, render the strength of such a flange on the hose inadequate.

Accordingly, a flanged hose may have - a pressure-resistant ring provided at the junction between the tubular portion of the hose and the flanged end thereof.

In the case of a flanged hose as described in our prior patent specification No. 1,397,432, such a pressure-resistant ring may be seated at the junction between the tubular portion and the flange of the outer flanged ring. It may therefore itself be embedded within the flexible material of the hose.

One such flexible material which provides a very high tensile strength, low transmission of vibration noise and good fire-retardant properties is a cloth made from Kevlar #(Registered Trade Mark), Kevlar being a material manufactured by The Dupont Company. The composition of this material may be found from United Kingdom Patent Secifications Nos. 1,198,081/2/3 and United Kingdom Patent Specifications Nos. 1,283,064/5/6 in the name of E.I. Do Pont de Nemours & Company. In summary, it comprises an extruded aromatic polyamide fibre, or aramid yarn, prepared with or without heat treatment, from an optically anisotropic dope of high molecular weight having recurring units of the formula:

Cloth is made from the Kevlar by weaving the fibres in criss-cross fashion.Cord is made from Kevlar by arranging the strands in the same direction, and providing only a ralatively weak transverse binding.

Thus there may be provided a hose comprising an extruded aromatic polyamide fibre or aramid yarn, preferably prepared from an optically anisotropic dope of high molecular weight having recurring units of the formula:

One of the hoses described and illustrated in our prior patent specification No. 1,397,432 is a curved section which turns through 90 degrees and which is known as an elbow hose. With certain materials of hose, and/or with hoses of large dimensions, the mandrel on which an elbow hose is formed may be difficult to remove after the construction of the hose has been completed. In some cases it may even be difficult to remove a straight mandrel from the inside of a straight hose section.

It is an aim of the present invention to reduce the difficulty with which the mandrel can be removed.

Accordingly, the present invention is directed to a mandrel comprising at least two parts which are joined together by means of an elongate component which passes through at least one of the parts and which has one end attached to one of the parts and its other end attached to the other part or another part, means being provided for releasing the elongate member from at least one of the points of attachment.

With such a mandrel, the elongate component can be released at one of its points of attachment to enable first one section of the mandrel to be removed from the hose and then the other.

This is particularly advantageous for the manufacture of an elbow hose in which the mandrel is curved, because if the mandrel were a single component, a force on one end of the mandrel, after completion of the manufacture of the hose, would be very strongly resisted by frictional forces at the other end of the mandrel. With a curved mandrel for an elbow hose, the elongate component may itself need to be curved. Advantageously in this case, therefore, the elongate component is flexible, and may for example be a bicycle chain or motor cycle chain or other heavy duty chain.

Two examples of a mandrel made in accordance with the present invention, are illustrated in the accompanying drawings, in which Figure 1 shows a partly axial sectional view of a flanged end of a hose; Figure 2 is a partly sectional side view of an elbow hose; Figure 3 is a partly sectional side view of the hose shown in Figure 2 viewing it in the direction indicated by the arrow III; Figure 4 shows a mandrel for use in the manufacture of the elbow hose shown in Figures 2 and 3; and Figure 5 is a partly axial sectional view of a second construction of mandrel for use in the manufacture of a modified elbow hose.

Figure 1 shows a flanged end of a hose 10 made of flexible material 12 such as a cloth made from Kevlar (Registered Trade Mark). It will be appreciated here that although the material is said to be flexible, this is only so when the hose is subjected to high forces, much greater than could normally be exerted by hand. A tubular embedded woven reinforcing stainless steel braid 14 extends longitudinally inside the tubular flexible material 12. Two annular reinforcing plates 16 and 18 are embedded within the flange 20 of the end of the hose 12. Each reinforcing plate has a tubular portion 22 or 24 respectively extending from its inner periphery inwardly into the hosing. The tubular portions 22 and 24 fit snugly within one another to form a friction fit, and the annular plates 16 and 18 fit one against the other. Each annular plate 16 or 18 is crimped to have two concentric circular ribs 26 and 28 protruding in the direction of the tubular hosing. The protuberances of the ribs of one of the plates fits in the recesses of the ribs -on the other plate. The end of the tubular stainless steel braiding 14 is sandwiched between the tubular portions 22 and 24, and turns through a right-angle, at the outer ends of those tubular portions where it is spayed out and extends between the flanged plates 16 and 18 to the outer peripheries thereof so that the crimped ribs increase the frictional engagement of the stainless steel braiding within the reinforcing plates 16 and 18. Also embedded in the flexible material of the flanged end of the hose is a pressure-resistant ring 30.This surrounds the tubular portions 22 and 24 of the reinforcing plates 16 and 18, fitting closely against the outer ring portion 22, and is also seated in the corner between the outer ring 22 and the reinforcing plate 16 and against that plate.

Two metallic semi-circular support ring sections 32 fit around the hose 12 to cover the flange 20 thereof on the side closer to the tubular part of the hose, and also to cover a larger part of the outer periphery of the flange 20.

The flanged hose shown in Figure 1 is made as follows A sleeve of uncured flexible material 36 is slid on to a mandrel 34 which has a uniform cylindrical cross-section.- The stainless steel braiding 14 is then woven around the outside of this sleeve 36. The pressure-resistant ring 30 is then slipped on to the tubular portion of the reinforcing plate 16 and then the two together are slid on to the outside of the stainless steel braiding 14. The latter is then splayed out so that it extends across the front face of the reinforcing plate 16 ^whereafter the second plate 18 is slid on to the end of the sleeve 36 so that its tubular portion 24 slips underneath o the stainless steel braiding 14.The two tubular portions 22 and 24 form a tight fit with the braiding sandwiched between them, and the two plates are pressed together to pinch the braiding between their circular concentric ribs 26 and 28. The plates 16 and 18 are then rivetted, or spot welded, or otherwise fixed together. An outer uncured sleeve of flexible material 38 is then slid around the stainless steel braiding 14, and the flange of flexible material 20 is built up around the outsides of the pressure-resistant ring 30 and the reinforcing plates 16 and 18. Thus assembled, the hose is put through a heat treatment to vulcanise or cure the flexible material 12 on the mandrel 34 which is subsequently slid out from the hose to leave the finished article.

As an alternative to curing or vulcanising, the sleeves 36 and 38 may be moulded around the mandrel 34.

A flanged elbow hose can be made in this way using a curved mandrel, the curve extending through a 90 degree turn, as shown in Figures 2 and 3. A number of through-holes 40 may be drilled through the flanges at the two ends of the hose. These through-holes 40 are spaced apart around the annular flange, and may be used for bolting the end of the hose to another such flange or to an inlet or outlet port.

Figure 4 shows a mandrel suitable for the manufacture of an elbow hose such as is shown in Figures 2 and 3. It comprises four hollow sections 42, 44, 46 and 48 in that order. The two end sections 42 and 48 are straight and the two middle sections 44 and 46 are each arcuate turning through 45 degrees and combining together to form a complete turn of 90 degrees. The sections 42 and 44 are joined together by means of a screw-threaded connection 50.

Likewise, the sections 46 and 48 are connected together by a screw-threaded connection 52. A cylindrical section 54 having a diameter which is less than the outer diameter of the mandrel sections but greater than their internal diameter is fixed in that end of the section 44 which is adjacent to the section 46 to provide a circular shoulder 56 projecting towards that section 46. In the adjacent end of the latter section there is formed a circular recess 58 having a diameter slightly in excess of the cylindrical section 54 so that the latter fits snugly into the recess 58. The circular shoulder 56 is chamfered to guide the adjacent end of the mandrel section 46 on to the cylindrical section 54 so to align the axes of the two mandrel sections 44 and 46.

The outside face of the cylindrical section 54 is provided with -a connector lug 59.

The free end of the mandrel section 48 is closed by a cap 60 which has a locating pin 62 extending into the material of the mandrel section 48. This prevents the cap 60 from rotating relative to the mandrel section 48. A square-sectioned central hole 64 extends axially through the centre of the cap 60. A bolt 66 having a square-sectioned shank 68 extending through the axial hole 64 has a screw-threaded free end 70 and, at its other end, inside the mandrel section 48, a connector lug 72. The screw-threaded end 70 projects outwardly from the cap 60, and a nut 74 is threaded on to that screw-threaded end.

A bicycle chain 76 extends through the mandrel sections 46 and 48, and has one end connected to the lug 72 and its other end connected to the lug 59. The mandrel sections 44 and 46 can be brought tightly together by tightening the nut 74. This draws the bolt 66 outwardly through the cap 60, pulling the lugs 72 and 59 closer together, until the cylindrical section 54 is pulled fully home into the recess 58.

The elbow hose as shown in Figures 2 and 3 can now be formed on the thus-completed mandrel as described hereinbefore. Once the flexible material of the hose has been cured, or thermosetif itisna plastic, the nut 74 can be loosened from the bolt 66. The latter is now free to slide out of the cap 60 into the interior of the mandrel section 48, which can now be pulled away from the hose to slide the curved section 46 out of the hose interior. The other end of the mandrel, at the section 44, can now be used to pull the curved section 44 out of the hose interior in the other direction.

The connector lug 59 may be attached to the cylindrical section 54 by a screwthreaded engagement. This assists in re-assembly of the mandrel. Thus the lug 59 can be unscrewed from the section 54, and the cap 60 lifted off from the mandrel section 48. The bolt 66 can now be reinserted through the hole 65 in the cap 60, and the nut 74 put back on the bolt 66. With the mandrel sections 46 and 48 positioned more or less upright, the chain 76 can now be lowered therethrough until the cap 60 re-engages the outer end of the section 48. The bolt 59 is now re-threaded into the cylindrical sections 54, and finally, the nut 74 is once again tightened to complete the re-assembly of the mandrel.

The mandrel sections may be made of any rigid material that will not interfere with the curing or thermosetting of the hose, such as a metal or a ceramics material.

In the construction of mandrel shown in Figure 5, which is entirely symmetrical about the line X-X, the right-angle turn is concentrated more at the centre of the mandrel, so that the finished hose made with such a mandrel comprises two relatively long straight portions at right angles to one another and connected by a relatively short curved portion which is integral with both straight portions. The two ends of the mandrel itself are more or less the same as the free end of the mandrel section 48 shown in Figure 4, and parts in Figure 5 corresponding to the parts of that free end in Figure 4 have the same reference numerals. Instead of a locating pin 62, the cap 60 and mandrel section 48 are positioned relative to one another by a key 78 on the inside of the section 48 which engages a keyway 80 in the cap 60.

The 90 degree bend in the mandrel is made up of seven parts altogether, which are positioned relative to one another by keys and keyways or locating pins such as that labelled 82 in Figure 5. Part of the 90 degree bend is taken up on the outside by curved portions 84, one on each of the two straight sections. A corner piece 86 completes the outside curve of the bend between the curved portions 84, and has two mutually perpendicular faces 88 and 90 which abut respective faces of the two straight sections. On each face 88 and 90, a bolt 92, having a connecting lug 94 fastened to one end of the chain 76, engages the corner piece 86 in a screw-threaded blind hole 95 therein. Inside curved segments 96, with intermediate segments 98 (only one of which is shown for clarity), complete the inside of the bend.With both bolts 74 tightened to stretch the chains 76, the complete mandrel behaves as a single component for the purpose of forming an elbow hose around it. After curing, the bolts 74 are removed, then the straight sections of the mandrel, then the remaining pieces fall out or are fished out.

It will be appreciated that each flexible chain 76 could be replaced by a rigid rod.

Numerous variations and modifications to the illustrated hose and mandrels may occur to a reader familiar with the art without taking the article outside the scope of the present invention-,- - For example, in the case of -the mandrel shown in Figure 4, the lug 59 could be omitted, the cylindrical section 54 made in the form of a ring, the chain 76 doubled in length, and a cap assembly arranged in the outer end of the section 42 in precisely the same way as that on the end of the section 48.

The hose may be built up by applying a liner of nitrile around a steel mandrel, then a sleeve of Kevlar 49 (RTM) cord, followed by stainless steel braiding (15g wire), then neoprene, then Kevlar 49 (RTM) cloth, neoprene, cloth, neoprene, cloth, a further stainless steel braiding (21g wire), neoprene, cloth, neoprene, a cleaning with Chemlok 233 (RTM), and a final layer of neoprene. The whole composite is then cured at 40 psi raised in 20 minutes and held for 40 minutes. Of considerable value in improving the adherence between the cloth and the neoprene is the prior cleaning or etching of the cloth in Chemlok 607 (RTM), drying, and further dipping the cloth in Chemlok 233 (RTM).

Claims (9)

Claims

1. A mandrel comprising at least two parts which are joined together by means of an elongate component which passes through at least one of the parts and which has one end attached to one of the parts and its other end attached to the other part or another part, means being provided for realeasing the elongate component from at least one of the points of attachment.

2. A mandrel according to claim 1, in which at least one of the parts is curved.

3. A mandrel according to claim 2, in which the said at least two parts are curved.

4. A mandrel according to any preceding claim, in which the elongate component is flexible.

5. A mandrel according to claim 4, in which the elongate component comprises a chain.

6. A mandrel according to claim 5, in which the chain is a bicycle chain.

7. A mandrel according to claim 5, in which the chain is a motor cycle chain.

8. A mandrel substantially as described herein with reference to Figure 4 or Figure 5 of the accompanying drawings.

9. A method of making a hose using a mandrel as claimed in any preceding claim, in which the hose is formed on the mandrel, and then the elongate component is released from at least one of its points of attachment to enable first one part of the mandrel to be removed from the hose, and then the other or each other part.